There is no doubt that the mean body weight of our population is continuously rising. In this context it is interesting to know that running--compared to cycling--results in a higher decrease of subcutaneous adipose tissue and has therefore a favourable influence on body weight. But public opinion still assumes that running provokes arthritis. This is used as a pretext against regular running training. In this overview we would like to show that running does not increase the risk of arthritis contrary to physical inactivity and overweight. Runners do not show a higher risk of developing joint arthritis on their lower extremities. However, frequency of arthritis is significantly higher in inactive and obese persons.